Drop-tube steam-generator



(Nomodel.) y

G. A. CURTIS 8E R. CUNNINGHAM.

9 DEOP TUBE STEAM GENERATOR. NQ. 560,397. -Patented May 19, 1896.

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AN DREW BLRAIMM. HDTUUTWUWAIMINGOK D C,

NITED STATES PATENT. OFFICE.

GEORGF. A. CURTIS AND RUEL CUNNINGHAM, OF BOSTON, MASSACHUSETTS.

i DROP-TUBE STEAM-GENERATOR.

SPECIFICATION forming part of Letters Patent No. 560,397, dated May- 19,1896.

Application tiled January 25, 1896. Serial No. 576,888. (No model.)

T0 all whom t may concern:

Be it known that we, GEORGE A. CURTIS and RUEL CUNNINGHAM, of Boston, inthe county of Suffolk and State of Massachusetts, have invented certainnew and useful Improvements in Drop-Tube Steam-Generators, of which thefollowing is a specification.

This invention relates to boilers or steamgenerators of the drop-tubetype, comprising a substantially horizontal steam-drum, a series ofinclined drop-tubes located below the drum and separated therefrom by anintervening space, and a fire-box below said tubes, the arrangementbeing such that the products of combustion from the fire-box passupwardly through the spaces between the forward portions of the tubesand into the space between the tubes and the drum, then pass downwardlythrough spaces between the central portions of the tubes, and finallyupwardly through the spaces between the rear portions of the tubes.

Our invention has for its principal object to provide efficient meansfor at once facilitating the combustion of the unconsumed gases in thespace between the forward portions of the tubes and the drum and forcausing the impingement of the burning products of combustion againstthe drum to the end that their thermal efficiency may bethoroughlyutilized.

The invention also has for its object to provide means for morethoroughly utilizing those products of combustion that pass between theintermediate and rear portions of the tubes.

The invention consists in the several improvements which we will nowproceed to describe and claim.

Of the accompanying drawings, forming a part of this specification,Figure l represents a partial side elevation and partial verticalsection of a steam-generator embodying our improvements. Fig. 2represents a perspective view of one of the heat-radiating guidesemployed over the forward portions of the tubes. Fig. 3 represents aperspective view of one of the heat-retarding bars or plates placed overthe intermediate and rear portions of the tubes. Fig. 4 represents aperspective View of oneof the heat-retarding bars placed below theintermediate portions of the tubes. Fig. 5 represents a perspective viewof one of the devices used for supporting the bar shown in Fig. 4. Fig.6 represents a section on line 6 6 of Fig. l. Fig. 7 represents aperspective view of one of the stoppers.

The same letters of reference indicate the same parts in all thefigures.

In the drawings, a represents the horizontal drum, and b b the inclineddrop-tubes, of a boiler or steam-generator of' the Babcock dt VVilcoXtype, the tubes being connected with each other at their ends bysuitable headers cc, said headers being connected in the usual mannerwith the drum a.'

d represents the fire-box, arranged below the forward portions of thetubes.

e represents the baffle-plate, which extends upwardly from thebridge-wall d, and separates the forward portions of the tubes Z9 fromthe central or intermediate portions, and f represents the rearbaffle-plate, which separates the intermediate portions of the tubesfrom the rear portions thereof, all being of a common and well-knownconstruction.

The tubes b are separated from the drum by a space which, owing to theinclination of the tubes, increases in height from the front to the rearends of the tubes, so that the products of combustion which are guidedupwardly by the baflie-plate c betweenthe forward port-ions of the tubesnaturally tend to pass rearwardly through the wider portion of saidspace, avoiding the narrower forward portion, the result being that theheat is not utilized upon the portion of the drum directly over thelire-box asfully as is desirable.

In carrying out our invention we provide a series of guides ordeflectors h, extending across the upper row of tubes and projectingupwardly from the tubes into the space be-A tween the tubes and the drumct. Said guides, which are made of refractory material, such aslire-brick, are preferably supported by the tubes and are separated fromeach other by spaces t', through which the products of combustion pass,said spaces being made successively narrower from the front to the rearend of the series, as shown in Fig. 1, so that portions of the productsof combustion are deiiected forward, the products being thus distributedalong the entire length of the for- IOO ward portions of the tubes morethoroughly than would be the case if the openings were all of the samewidth, in which event the greater volume of the products of combustionwould pass through the rear openings. Owing to the inclination of thetubes we inake the guides h of varying height, the guides graduallyincreasing in height from the front to the rear end of the series, asshown in Fig. l, the increase being such as to make the upper ends ofall the guides of practically the saine height, so that the products ofcombustion are guided upwardly to the same extent by each guide. XVeprefer to make each guide h of the general form shown in Fig. 2, theguide having a relatively broad base adapted to rest upon the series oftubes and being reduced in thickness at its upper portion, so that itcan be readily chipped off to reduce its height, it being our intentionto make all of the guides of the saine height, so that they can befitted to any d rop-tube boiler, whether the inclination of the tubes begreater or less than that shown in Fig. l. In order that the guides maybe readily reduced in height, we provide grooves 7d, which are parallelwith the upper edges of the guides and guide the workman in chipping olfthe 'material Each guide is provided with spacing lugs or projections h2h2, projecting laterally from one edge lof the base of the guide andabutting against the adjacent surface of the next guide. The said lugsaie preferably made of uniform length or projection in all the guidesand chipped olf when the guides are beingassembled to give the desiredvariation in the width of the spaces t'. \Ve prefer to interpose adeflecting-plate j of fire-brick between the baffleplate e 'and theadjacent guide h, and to interpose asimilar plate j between the upperheaders c and the 'ad jacent guide 7L, as shown in Fig. l. It will beseen that the guides 7L, arrailged as shown and separated by theintermediate spaces, not only distribute `and guide the products ofcombustion upwardly, causing them to impinge against the drinn a, butalso become highly heated and radiate heat upon the gases passingbetween them, thus promoting the combustion of said gases.

Although we have described a series of guides 7L, it is obvious that asingle guide arranged to deii'ect the products of combustion upwardlyand to radiate heat for the purpose of promoting combustion would givein part the advantages above set forth, and we therefore do not'liinitoiirselves to the employment of a series of guides.

ln Fig. l we show the balfl'e-plate e pro-` vided with an extension e',projecting upwardl y into the space between the tubes and the drum, saidextension being preferably protected by a facing of fire-brick e2-an'dconstituting an upwardly-proj ectin g guide,which may be used eitherwither withoiitthe series of guides 7L. XVe iind that by thus defiectingthe products of combustion upwardly and causing them to pass alonghighly-heated refractory surfaces above those portions of the tubeswhich are located over the fire-box wc effect a material saving of fueland utilize to a marked degree its thermal efficiency.

Our improvements also include means for retarding the products ofcombustion in their course from the space between the drum and the tubesthrough the intermediate and rear portions of the tubes. Ve have hereshown three sets of devices for accomplishing this result, namely:

First, a series of bars or plates 7u 7o of firebrick of substantiallythe form shown in Fig. 3, adapted to rest upon the upper row of theintermediate portions of the tubes, said plates having spacing lugs `orprojections 7a', which form spaces between the plates for the passage ofproducts of combustion.

Second, bars or plates k2, suspended from the lower row of theintermediate portions of the tubes, said bars being of the form shown inFigi and provided with hangers 7a3, formed, as shown in Fig. 5, withhooked ends to engage the tubes and support the bars k2 below the tubes,said bars having spacing lugs or projections 7a4. lVe prefer to make theupper sides of the bars k2 augiilar, as shown, in order that they mayshed the ashes and soot that fall upon them.

Third, a series of bars or plates 7s, placed upon the upper row of therear portions of the tubes behind the baffle-plate f, said plates beingformed like the plates k and having similar spacing lugs or projections.

We may use either one of the above-described series of retarding-bars,the other two being omitted, or the three series may be used, as shown.rlhe result 0f these spacingbars is to retard the products ofcombustion, first, in the space between the drum and tubes, causing theheat to be more thoroughly utilized upon the drinn; secondly, in thespaces between the intermediate portions `of the tubes, and, thirdly, inthe spaces between the rear portions of the tubes.

The headers c, that connect the tubes inareof the sinuous form shown inFig. G and are separated from each other by spaces c', through which aconsiderable proportion of the produ'cts of combustion escape into thespace behind the series of tubes without passing upwardly to the space`above the rear portions of the tubes. To prevent this loss of heat, wehave provided a series of Stoppers for the spaces between the sinuousheaders, as shown in Figs. 6 and 7, each stopper being a bar m, havingprojections m' formed on one edge, the bar and projections being adaptedto be inserted flatwise between two horizontal rows of tubes, asindicated at the bottom of Fig. 6, and after its insertion theprojections m may be inserted between the tubes by giving the bar aquarter-turn, the projections being formed to partially fill the spacesbetween the tubes, as indicated in Fig. 6. These stoppers may be made offire-brick or any other suitable material.

ICO

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The bars or guides 7L iirst described may be considered retarding-barsin that they retard the passage of products of combustion upwardlybetween the forward portions of the tubes, and in this respect they areequivalents of the bars 7a k2 765. We believe that a bar of refractorymaterial adapted to extend across the tubes of a drop-tube boiler andprovided with spacing projections which form spaces for the passage ofthe products of combustion between the bars is new with us, and wetherefore desire to cover the same as broadly as possible within legalbounds.

l. In a drop-tube steam-generating apparatus, the combination with thedrum, droptubes, and fire-box, of a series of heat-radiating bars orguides of refractory material supported by the upper row of tubes overthe fire-box and projecting above said tubes to guide the products ofcombustion upwardly toward the drum, said guides being separated byspaces for the passage of the products of combustion.

2. In a drop-tube steam-generating apparatus, the combination with thesubstantially horizontal drum, the inclined drop-tubes, and

the fire-box, of a series of heat-radiating bars or guides of refractorymaterial supported by the upper row of tubes over the fire-box andseparated from each other by spaces, said guides increasing` in heightfrom the front to the rear end of the series, whereby their upper edgesare located at substantially the same height.

3. In a drop-tube steam-generating apparatus, the combination with thedrum, droptubes, and fire-box, of a series of heat-radiating bars orguides of refractory material supported by the upper row of tubes overthe fire-box and projecting above said tubes, said guides beingseparated from each other by duced upper portion which is longitudinallygrooved to facilitate a reduction of the height of the guide.

6. The combination with the fire-box, the drum, the drop-tubes, and thebaffle-plates, of a series of retarding plates or bars of refractorymaterial suspended from the intermediate portions of the lower row oftubes7 said bars being separated by spaces.

7. A retarding-bar having spacing progections and hangers whereby it maybe suspended from boiler-tubes.

8. A drop-tube boiler comprising the drum, the drop-tubes, the fire-box,the distributing and guiding bars located above the forward portions ofthe tubes over the fire-box, the retarding-bars located above theintermediate portions of the tubes, the suspended retarding-bars locatedbelow the said intermediate portions,and the retarding-bars locatedabove the rear portions of the tubes.

In testimony whereof we have signed our names to this specication, inthe presence of two subscribing witnesses, this 18th day of January7 A.D. 1896.

GEO. A. CURTIS. RUEL CUNNINGHAM.

Witnesses I-IAZEN CURTIS, O. F. BROWN.

